Patient implanted with a single-chamber defibrillator (Visia AF XT VR) for dilated cardiomyopathy.
1, 2. What diagnosis do you suggest from this graph?
This episode was classified as TVR (1); the graph shows a sudden acceleration with cycles detected mainly in the TVR zone; detection of a TVR episode effectively treated by a burst.
- What is your diagnosis?
The EGM shows a regular, monomorphic tachycardia, detected in the TVR zone; the TF. marker indicates that the defibrillator is programmed with a TVR zone via FV.
- What therapy is delivered?
The VF counter was filled with 30 cycles out of 40 classified as TF; analysis of the 8 cycles preceding the diagnosis found only TF cycles with no FS cycle leading to the diagnosis of TVR; the first therapy in the TVR zone, a burst, was delivered; reduction of the arrhythmia.
- How many zones are programmed?
The way in which the zones are programmed can be difficult to understand; you might think that the FV zone starts at 188 bpm and stops at 222 bpm, with the TVR zone starting at 222 bpm; in fact the opposite is true: TVR from 188 to 222 bpm and FV above 222 bpm; the TVR zone is programmed via FV; this reflects the fact that the same FV meter is used from 188 bpm.
Messages to remember
- When a TVR zone is programmed, it is possible to choose programming via TV or via FV; depending on the choice, the TV counter (consecutive cycles) or the FV counter (probabilistic) is used.
- As in this example, when a TVR zone is programmed via FV, the same FV counter is used for the TVR zone and the FV zone; the TF. and FS classified cycles therefore implement the same probabilistic FV counter.
- When the VF counter is completed, the device analyses the last 8 intervals; if at least one of the intervals is classified as FS, the diagnosis is VF and the therapies in the VF zone are delivered; if none of the last 8 intervals is classified as FS, the diagnosis is TVR and the therapies in the TVR zone are delivered.